How to Tell If Your Trailer Brakes Need Service

Trailer brakes do most of the work of stopping a loaded rig, but they're easy to ignore until something goes wrong. Catching a weak magnet, worn shoe, or wiring fault early keeps you and everyone behind you safe. Walk through these checks before a big tow or at least twice a season.

Estimated time: 30 minutes

Tools You'll Need

• Brake controller in the tow vehicle
• Jack and jack stands
• Multimeter (optional)

Step-by-Step

Step 1: Test the brake controller response

With everything hooked up, use the manual slider on your brake controller while rolling slowly. You should feel the brakes grab. No response, or a 'no trailer connected' fault, points to a wiring or magnet problem.

Step 2: Listen and feel during a test stop

On a quiet road, make a few firm stops. Grinding, squealing, or a pull to one side means worn shoes, contaminated linings, or uneven brake force between axles.

Step 3: Check for weak or uneven braking

If the rig feels like it's pushing the truck or takes much longer to stop than usual, your brakes are underperforming — often from worn magnets, glazed shoes, or low gain settings.

Step 4: Inspect the wiring and connector

Look over the 7-pin connector and the wiring along the frame for corrosion, chafing, or loose grounds. A bad ground is one of the most common causes of weak or dead brakes.

Step 5: Pull a drum and inspect the shoes

Safely jack up the frame, remove a wheel and drum, and check the brake shoes. Replace them if the lining is under 1/16 inch, cracked, or soaked with grease from a leaking seal.

Step 6: Check the magnets

Inspect each magnet for flat spots or uneven wear and confirm it sits flush against the drum. Worn magnets give weak, grabby braking and should be replaced in pairs per axle.

Step 7: Verify the breakaway system

Pull the breakaway pin with the wheels chocked — the brakes should lock fully. Confirm the breakaway battery holds a charge, since this is your last line of defense if the rig comes loose.

Need a Hand?

If your brakes fail any of these checks, don't tow until they're fixed. Allred Trailer Service diagnoses and repairs electric brakes, magnets, and controllers on-site across the Sacramento area — text (916) 251-9731 for a quote.

Frequently Asked Questions

What are the main signs electric brakes need service?

Key warning signs include: the rig pushing the truck during stops, pulling to one side under braking, grinding or squealing from the axle area, no response from the brake controller manual override, a "no trailer connected" fault on the controller, or a breakaway battery that won't hold charge.

How do I test brakes without removing the drums?

Use your brake controller's manual override slide while rolling slowly — you should feel the brakes engage. Then make several firm stops on a quiet road and listen for grinding, squealing, or uneven pull. A voltmeter at the 7-pin connector can confirm the brake circuit is delivering voltage before going further.

How thick should brake shoe lining be before replacement?

Replace brake shoes when friction lining is worn to 1/16 inch or less. Also replace immediately if the lining is contaminated with grease or oil from a leaking hub seal — contaminated shoes cannot be cleaned and reused safely.

How long do electric brake shoes last?

Under normal use, electric brake shoes typically last 30,000–50,000 miles depending on load, terrain, and frequency of use. Properly burnished shoes on a correctly adjusted axle last significantly longer than those that were never seated. If you're not sure whether the brakes have ever been burnished, treat them as unserviced.

How do I test the breakaway system?

With the wheels chocked so the rig cannot roll, pull the breakaway pin from the switch. The brakes should lock fully and hold stationary. Confirm the breakaway battery reads at least 12.4V at rest. A dead breakaway battery is a common finding on rigs that sit for months between uses — charge it at least every 90 days.